﻿Shader "UnityShaderBook/Chapter8/AlphaBlendBothSide"   //p189开启深度写入的透明度混合
{
	Properties{
		_Color("Color Tint", Color) = (1, 1, 1, 1)
		_MainTex("Main Tex", 2D) = "white" {}
		_AlphaScale("Alpha Scale", Range(0, 1)) = 1 //用于在透明纹理的基础上控制整体的透明度
	}
	SubShader{

		Tags{
			"Queue" = "Transparent" //透明度混合使用的渲染队列是名为"Transparent"队列
			"IgnoreProjector" = "True"//这个shader不会受到投影器（Projector）影响
			"RenderType" = "Transparent" //让Unity把这个Shader归入到提前定义的组（这里是Transparent组），以指明该shader是一个使用了透明度混合的shader
		}


		Pass
		{
			Tags{ "LightMode" = "ForwardBase" }

			//Frist Pass renders only back faces
			Cull Front
			ZWrite Off//***关闭深度写入***
			Blend SrcAlpha OneMinusSrcAlpha//设置该pass的混合模式，将源颜色（该片元着色器产生的颜色）的混合因子设为ScrAlpha，
										   //目标颜色（已经存在于颜色缓冲中的颜色）的混合因子设为OneMinusSrcAlpha

			CGPROGRAM

			#pragma vertex vert
			#pragma fragment frag

			#include "Lighting.cginc"

			fixed4 _Color;
			sampler2D _MainTex;
			float4 _MainTex_ST;
			fixed _AlphaScale;


			struct a2v
			{
				float4 vertex : POSITION;
				float3 normal : NORMAL;
				float4 texcoord : TEXCOORD0;
			};

			struct v2f
			{
				float4 pos : SV_POSITION;
				float3 worldNormal : TEXCOORD0;
				float3 worldPos : TEXCOORD1;
				float2 uv : TEXCOORD2;
			};

			v2f vert(a2v v)
			{
				v2f o;

				o.pos = UnityObjectToClipPos(v.vertex);

				o.worldNormal = UnityObjectToWorldNormal(v.normal);

				o.worldPos = UnityObjectToWorldDir(v.vertex).xyz;

				//o.uv = v.texcoord.xy * _MainTex_ST.xy + _MainTex_ST.zw;
				o.uv = TRANSFORM_TEX(v.texcoord, _MainTex);

				return o;
			}

			fixed4 frag(v2f i) :SV_Target
			{
				fixed3 worldNormal = normalize(i.worldNormal);
			fixed3 worldLightDir = normalize(UnityWorldSpaceLightDir(i.worldPos));

			fixed4 texColor = tex2D(_MainTex, i.uv);

			fixed3 albedo = texColor.rgb * _Color.rgb;

			fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz * albedo;

			fixed3 diffuse = _LightColor0.rgb * albedo * max(0, dot(worldNormal, worldLightDir));

			return fixed4(ambient + diffuse, texColor.a * _AlphaScale);
			}
				ENDCG
		}

		Pass
		{
			Tags{ "LightMode" = "ForwardBase" }

			//Frist Pass renders only back faces
			Cull Back
			ZWrite Off//***关闭深度写入***
			Blend SrcAlpha OneMinusSrcAlpha//设置该pass的混合模式，将源颜色（该片元着色器产生的颜色）的混合因子设为ScrAlpha，
										   //目标颜色（已经存在于颜色缓冲中的颜色）的混合因子设为OneMinusSrcAlpha

			CGPROGRAM

			#pragma vertex vert
			#pragma fragment frag

			#include "Lighting.cginc"

			fixed4 _Color;
			sampler2D _MainTex;
			float4 _MainTex_ST;
			fixed _AlphaScale;


			struct a2v
			{
				float4 vertex : POSITION;
				float3 normal : NORMAL;
				float4 texcoord : TEXCOORD0;
			};

			struct v2f
			{
				float4 pos : SV_POSITION;
				float3 worldNormal : TEXCOORD0;
				float3 worldPos : TEXCOORD1;
				float2 uv : TEXCOORD2;
			};

			v2f vert(a2v v)
			{
				v2f o;

				o.pos = UnityObjectToClipPos(v.vertex);

				o.worldNormal = UnityObjectToWorldNormal(v.normal);

				o.worldPos = UnityObjectToWorldDir(v.vertex).xyz;

				//o.uv = v.texcoord.xy * _MainTex_ST.xy + _MainTex_ST.zw;
				o.uv = TRANSFORM_TEX(v.texcoord, _MainTex);

				return o;
			}

			fixed4 frag(v2f i) :SV_Target
			{
				fixed3 worldNormal = normalize(i.worldNormal);
				fixed3 worldLightDir = normalize(UnityWorldSpaceLightDir(i.worldPos));

				fixed4 texColor = tex2D(_MainTex, i.uv);

				fixed3 albedo = texColor.rgb * _Color.rgb;

				fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz * albedo;

				fixed3 diffuse = _LightColor0.rgb * albedo * max(0, dot(worldNormal, worldLightDir));

				return fixed4(ambient + diffuse, texColor.a * _AlphaScale);
			}
			ENDCG
		}
	}
	FallBack "Transparent/VertexLit"
}
